qapi-schema: dump-guest-memory: Improve text

dump-guest-memory is supported by more than just x86, however
the paging option is not.

(No functional change.)
Signed-off-by: NAndrew Jones <drjones@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-id: 1452542185-10914-2-git-send-email-drjones@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

qapi-schema.json

@@ -2169,8 +2169,7 @@
 # @dump-guest-memory
 #
 # Dump guest's memory to vmcore. It is a synchronous operation that can take
-# very long depending on the amount of guest memory. This command is only
-# supported on i386 and x86_64.
+# very long depending on the amount of guest memory.
 #
 # @paging: if true, do paging to get guest's memory mapping. This allows
 #          using gdb to process the core file.
@@ -2186,6 +2185,7 @@
 #             2. The guest can be in real-mode even if paging is enabled. For
 #                example, the guest uses ACPI to sleep, and ACPI sleep state
 #                goes in real-mode
+#             3. Currently only supported on i386 and x86_64.
 #
 # @protocol: the filename or file descriptor of the vmcore. The supported
 #            protocols are: